When we create size specs, is it fair to say that we use "average" body measurements when determining our final spec sheet measuremens? We utilize fit models, sizing research, experience, etc. However

When we create size specs, is it fair to say that we use "average" body measurements when determining our final spec sheet measuremens? We utilize fit models, sizing research, experience, etc. However, with all of the best intentions, how can we possibly create a perfect fitting garment when all people have different bodies. Putting aside custom fit clothing, I think that sizing may simply be nothing more then a guessing game. My height is approx. 6' 2" and I wear a size X-Large t-shirt (hey, you shouldn't call me fat..). Isn't it very probable that people that are 5' 8" tall also wear a size X-large t-shirt (depending on size of chest, shoulders, belly). My point being, when the shirt is produced the shirt length is the same for people that have a different length torso. If we are both wearing the same size shirt, yet we are different heights, how in the world could the shirt fit us "both" perfectly. Not possible... Taking this one step further, why do retail buyers bust our humps if we produce a shirt that is slightly out of tolerance? If the body measurements of people are rarely the same, why does the garment have to stay one hundred percent exact to the quarter of an inch... If we produce a t-shirt a bit longer then the size spec intended, does this mean the t-shirt will no longer fit anyone.. Actually, it may fit some people better then the original intended spec file. Anyway, I understand that fit must be consistent. However, we do NOT have an industry standard size spec. So, isn't this all rather silly. To make things even more complex, think about the women's body. Many different measurements indeed. If I selected ten random women that wear size medium tops and lined them up on a wall, my guess is that none of them would have the exact same body measurements. If you agree, you are welcome to list your thoughts in the comment section of this blog. If you do not agree, you are still welcome to list your comments (however, I may not like you any more.. just kidding.) Actually, we should probably ask questions about garment fit, in the pattern making group.